High strain-rate superplasticity of AZ91 alloy achieved by rapidly solidified flaky powder metallurgy

In this study, the authors successfully obtained high strain-rate superplasticity (HSRS) for an AZ91 Mg alloy using rapidly solidified flaky powder metallurgy (RS FP/M). The RS FP/M AZ91 shows an elongation to failure of 465% at a temperature and initial strain rate of 623 K and 10−2 s−1, respectively. Furthermore, the optimum superplastic strain rate for the maximum elongation was 10−2 s−1, which is higher than those attained by other methods. The HSRS obtained in this study is attributed to an effective grain refinement (∼1 μm) and high thermal stability. The bimodal grain structure may further contribute to HSRS.